Leetcode 24 Swap Nodes in Pairs

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* swapPairs(ListNode* head) {
        if (head == NULL || head->next == NULL) {
            return head;
        }
        
        ListNode* dummyHead = new ListNode(0);
        dummyHead->next = head;
        
        ListNode* prev = dummyHead;
        ListNode* cur = prev->next;
        ListNode* nex = cur->next;
        
        int len = 0;
        
        while(cur) {
            ++len;
            cur = cur->next;
        }
        
        while(len >= 2) {
            cur = prev->next;
            nex = cur->next;
            
            cur->next = nex->next;
            nex->next = prev->next;
            prev->next = nex;
            nex = cur->next;
            
            prev = cur;
            len -= 2;
        }
        
        ListNode* retHead = dummyHead->next;
        delete dummyHead;
        return retHead;
        
    }
};

  

 

  
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文章来源: blog.csdn.net，作者：herosunly，版权归原作者所有，如需转载，请联系作者。

原文链接：blog.csdn.net/herosunly/article/details/88173872